Gas safety shutoff

ABSTRACT

A system for igniting a grill can include a solenoid valve, a flame rectification sensor, an igniter, and a control circuit connected to the solenoid valve and the flame rectification sensor. The solenoid valve controls flow of gas to the grill&#39;s burner and includes a switch that closes when a handle connected to the switch opens the solenoid valve. The control circuit sends current to the solenoid valve when the switch is closed to hold the solenoid valve open. After the switch closes, the igniter is ignited. After ignition, the control circuit monitors the presence of a flame with a flame rectification sensor. If no flame is detected after a certain amount of time, the control circuit stops sending current to the solenoid valve to close the solenoid valve.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the priority benefit of U.S. Provisional PatentApplication No. 62/168,686, entitled “GAS SAFETY SHUTOFF,” filed May 29,2015, the entirety of which is incorporated herein by reference.

BACKGROUND

Grills or other cooking apparatuses use igniters to start flames. Forgas grills, a valve disposed along a gas line is operated to control aflow of gas to a burner, and an igniter disposed downstream of the valveis operated to ignite gas flowing through an open valve to start a flameat the burner.

SUMMARY

A grill can include a safety shutoff apparatus for added safety. In someaspects of the subject technology, a safety shutoff can shut off a flowof gas in response to detection of a lack of flame at a burner using aflame sensor. In some implementations of the subject technology a flamesensor can include one or more components subject to wear, degradation,contamination, or a combination thereof (e.g., contamination of a sensorrod or a circuit board), which may impair functioning of the flamesensor, such as, for example, by causing a magnitude of a flamedetection signal to drift over time, or diminishing reliability of theflame sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding and are incorporated in and constitute a part of thisspecification, illustrate disclosed embodiments and together with thedescription serve to explain the principles of the disclosedembodiments. In the drawings:

FIG. 1A illustrates a block diagram of a grill apparatus according toexample aspects of the present disclosure.

FIG. 1B schematically illustrates a grill apparatus according to exampleaspects of the present disclosure.

FIG. 1C illustrates a valve according to example aspects of the presentdisclosure.

FIG. 1D is an exploded view of the valve 110 of FIG. 1C.

FIG. 2 shows a flowchart of a process of automatically shutting off agas valve according to example aspects of the present disclosure.

FIGS. 3A-3D show tables corresponding to normal operating states for agas safety shutoff apparatus according to example aspects of the presentdisclosure.

FIG. 3E-3I show tables corresponding to additional operating states forthe gas safety shutoff apparatus according to example aspects of thepresent disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth to provide a full understanding of the present disclosure. It willbe apparent, however, to one ordinarily skilled in the art that theembodiments of the present disclosure may be practiced without some ofthese specific details. In other instances, well-known structures andtechniques have not been shown in detail so as not to obscure thedisclosure.

FIG. 1A illustrates a block diagram of a grill apparatus 100. FIG. 1Bschematically illustrates an example grill apparatus 100. FIGS. 1C and1D illustrate an example of a valve 110.

FIG. 1A illustrates the grill apparatus 100 comprising the valve 110, anigniter 120, a flame sensor 140, a control circuit 150, an LED 130, agas supply 160, a burner 170, a transformer 154, and a battery 152according to example aspects. The grill apparatus 100 may correspond toa grill, or another appliance that utilizes flame. The gas supply 160can comprise a source of combustible gas, such as, for example, a tankor continuous flow system. The grill apparatus 100 can comprise a singlevalve 110 for a single burner 170, or can comprise multiple valves 110for respective multiple burners 170, each valve being independentlycontrollable. For example, the grill apparatus illustrated in FIG. 1Bcomprises four valves 110 a, 110 b, 110 c, 110 d for respective burners170 a, 170 b, 170 c, 170 d. Two views of the four valves 110 a, 110 b,110 c, 110 d are shown in FIG. 1B. One view of the valves illustratesthe connection of the valves to a gas feed system. The other view of thevalves illustrates electrical connections between the vales, controlcircuits 150, the battery 152, and the transformer 154. Although FIG. 1Aillustrates the igniter 120 as comprising the flame sensor 140, in someaspects of the subject technology, the same combination of components(e.g., an electrode) can be operable to both ignite a flame and detectthe presence of a flame. In some aspects of the subject technology, theigniter 120 and the flame sensor 140 can be independent, sharing nocomponent between them.

FIG. 1B shows an example grill apparatus 100. In FIG. 1B, the grillapparatus 100 comprises multiple burners 170, including burners ofdifferent configurations, such as, for example, a sear burner 172 and arotisserie burner 174. The gas supply 160 (FIG. 1A) is coupled to aninlet 180 of the gas feed system. The gas feed system can include pipes,hoses, and/or other apparatus for conducting the flow of gas. The gasfeed system conducts gas from the gas supply 160 to each burner 170through respective valves 110. Each burner 170 is coupled to arespective igniter 120. Each valve 110 is coupled to a respectivecontrol circuit 150 and LED 130. The transformer 154 and the battery 152are connected to each control circuit 150.

The example valves illustrated in FIGS. 1A-1D each comprise a handle 112(e.g., a knob), a cam member 114, a solenoid 116, and a switch 118. FIG.1C illustrates an example valve 110 including its solenoid 116 and valvehandle 112. FIG. 1D is an exploded view of the valve 110 of FIG. 1C. Asshown for example in FIG. 1D, the valve 110 can comprise a valve body190, an inlet 192, and an outlet 194. The valve can comprise trim,including one or more seats (which may be formed by the valve body), oneor more valve members (e.g., plugs, balls, discs, etc.), and a stem 196.The valve member(s) can seal against the seat(s) to close a gas passagethrough the valve. The stem 196 can protrude from the valve body 190.The cam member 114 is attached to the stem 196 so that the stem moveswith the cam member. The cam member 114 is attached to the handle 112 sothat the cam member moves with the handle.

The valve 110 is connected to the gas supply 160. The valve 110 allowsgas from the gas supply 160 to flow through the valve when it is open,and prevents gas from flowing through the valve when it is closed. Thesolenoid 116 can comprise an electromagnet that holds open the valve 110when a current is provided, such as a current of about 180 mA. However,in some implementations of the subject technology, the solenoid 116 whenactivated by a current can hold the valve 110 open, but is unable toopen the valve 110 from a closed state. In other words, the valve 110may be mechanically opened through the valve handle 112 then held openby the solenoid 116, but cannot be pulled open by the solenoid alone. Avalve comprising a solenoid is referred to herein as a solenoid valve.

The valve 110 is opened by physical manipulation (e.g., rotation,depression, or a combination thereof) of the valve handle 112 tomechanically open a passage through the valve. The position of the valvehandle 112 can determine the extent to which the valve 110 is opened, tocontrol a flow rate of the gas. In some implementations of the subjecttechnology, the valve handle 112 is rotated counterclockwise whiledepressing it to open gas flow initially with depression not requiredfor adjustment of the extent of gas flow thereafter. The valve handle112 can be marked, for example, LO and HI, corresponding to a low flowrate, adjustable to a high flow rate. Manipulation of the valve handle112 can move the cam member 114, which can be connected directly to thehandle 112 and/or to a shaft (e.g., the stem 196) that is also connectedto the valve handle 112. The cam member 114 comprises a cam 198 that ispositioned, when the valve is assembled, to interact physically with theswitch 118 to selectively actuate it based on a position of the cammember 114 relative to the switch 118. Sufficient movement (e.g.,rotation) of the cam member 114 can close the switch 118. While thevalve 110 is open, such as any position from LO to HI, the switch 118can be closed by virtue of the position of the cam member 114.

The control circuit 150 can be an integrated circuit, and can compriseone or more sub-circuits. The control circuit 150 can comprise a singleprinted circuit board, or can be a master board with several slaveboards. The control circuit 150 can include or be coupled to a powersource. For example, the control circuit 150 can be powered by thetransformer 154, which can be as a 12 VDC, 5-8 Amp center-tappedtransformer. Additionally or alternatively, the control circuit 150 canbe powered by the battery 152. In some implementations, the transformer154 can trickle charge the battery 152. The control circuit 150 cancommunicate electrically with the igniter 120, LED 130, flame sensor140, solenoid 116, and switch 118.

When the switch 118 is closed (activated), the control circuit 150 sendsa current to the solenoid 116 of the valve 110. The current can be amillivolt current sent to the solenoid 116 of the valve 110. In FIG. 1B,solenoid control signals are sent through two wires, although in otherimplementations more or fewer wires can be used. The solenoid 116 holdsthe valve open under control of the control circuit 150 while the switch118 is closed.

The control circuit 150 can power the LED 130, so that it illuminates,when the switch 118 is activated, to indicate the attempt to light orignite the burner. The LED 130 can be a 1.5 VDC blue LED, which beginsflashing to indicate the ignition attempt. In other implementations, theLED 130 can be another color LED or other visual or audible indicator.

When the switch 118 is initially activated, the control circuit 150 cansend an ignition current to the igniter 120. The igniter 120 can be anyigniter configured to ignite a burner. For example, the igniter can be adirect-spark igniter, a hot-surface igniter (e.g., a ceramic hot-surfaceigniter), or any other electrically powered ignition system. In certainimplementations, the igniter 120 can also comprise the flame sensor 140.In some such implementations, flame sensing can be inactive duringapplication of ignition current to the igniter. For example, a detectionsignal, which can be an AC signal, can be continuously applied to theflame sensor 140, e.g., by the control circuit 150, to detect thepresence or absence of flame (e.g., when an AC signal is rectified by aflame to a DC signal). In some implementations, the detection signal isnot sent to the igniter, e.g., by the control circuit 150, while theignition current (e.g., a 12 VDC signal) is sent to the igniter. In someimplementations, the detection signal and ignition current can beswitched back and forth rapidly, e.g., by the control circuit 150, toachieve near-simultaneous ignition and flame sensing. In someimplementations, such as those wherein components of the igniter 120 andthe flame sensor 140 are separate or discrete, the detection signal canbe sent, e.g., by the control circuit 150, to the flame sensorconcurrently with application of ignition current to the igniter, e.g.,by the control circuit 150.

When the valve 110 is open (e.g., held open by a solenoid 116), theigniter 120 can ignite gas flowing toward the burner from the valve 110.As a safety precaution, gas flow can be shut off if the gas does notignite. For example, the igniter 120 can be on for a period, e.g., 5-6seconds, then turned off for a period, e.g., 3 seconds, while presenceor absence of a flame is detected.

In some implementations, presence or absence of a flame is detected by aflame sensor 140 by rectification of a detection signal passed throughthe flame sensor, which can be integrated partially or entirely with ordiscrete from the igniter 120. In some implementations, the flame sensordirect current of the detection signal through a location where a flamemay be present during normal burner operation. For example, the flamesensor can comprise an electrode positioned such that the location wherea flame may be present during normal burner operation is intersected byan arc of current between electrode components. The flame sensor 140 canbe activated, by sending the detection signal to the flame sensor,before ignition current is sent to the igniter 120. For example, inresponse to the switch 118 being activated, the control circuit 150 canactive the flame sensor 140, and after a sensor activation period, suchas 100 ms, the control circuit 150 can send an ignition current to theigniter 120. Alternatively, the flame sensor 140 can be always on whenthe grill apparatus 100 is on. The control circuit 150 can continuouslyor intermittently monitor the detection signal from the flame sensor 140through some or all of the process for igniting the correspondingburner. Additionally or alternatively, the control circuit 150 cancontinuously or intermittently monitor the detection signal from theflame sensor 140 after a process for igniting the corresponding burnerhas concluded.

A change in the detection signal can indicate the presence of flame, orsuccessful ignition. In some implementations, the control circuit 150monitors for sudden changes in the flame rectifier signal. For example,the detection signal can have a wave form when no flame is present, butflatten in response to flame rectification. In some implementations,presence or absence of a flame can be determined by the control circuitbased on an absolute value of a parameter of the detection signal (e.g.,voltage). Additionally or alternatively, presence or absence of a flamecan be determined by the control circuit based on a change (e.g., amagnitude of change) of a value of a parameter of the detection signal(e.g., voltage). In some implementations, presence or absence of a flamecan be determined by the control circuit based on a derivative of thedetection signal over a period including at a time before ignition orbefore an ignition process being.

Advantageously, some implementations of the subject technology candetect presence or absence of a flame independently of an absolutethreshold value of a parameter of the detection signal (e.g., voltage).In implementations wherein one or more component of the flame sensor 140(e.g., such as portions of the switch 118, the control circuit 150, or arod (e.g., of an electrode) protruding to a location where flame isexpected to be present continuously or intermittently during use of aburner) can be worn, degraded, contaminated, or a combination thereofover time, altering characteristics of the components that may causeabsolute values of the detection signal, in otherwise similarconditions, to drift. Thus, such wear, degradation, or contamination maycause inaccurate or unreliable determination of presence or absence of aflame based on an absolute value of a parameter of the detection signal,such as by determining whether an absolute value of a parameter of thedetection signal passes a static threshold value. Degradation can becaused by, for example, rusting of materials and resistivity changes dueto hot/cold cycles. Contamination can be caused by, for instance, salt,grease, or food contacting parts of the flame sensor 140. In someaspects of the subject technology, by determining presence or absence ofa flame based on identification of a change in the detection signal frombefore activating the igniter to a time during or after activating theigniter, rather than an absolute value, the effects of wear,degradation, contamination, or a combination thereof can be reduced.

For example, degradation to the flame sensor 140 can cause the absolutevalue of the detection signal received from the flame sensor to driftlower under otherwise similar circumstances. For example, a degradedflame sensor 140 may produce, when a flame is present, a detectionsignal having an absolute value that is below an absolute valuethreshold for detection based on flame rectification. On the other hand,even if an absolute value of a parameter of the detection signal drifts,a degraded flame sensor 140 can still produce a detection signal havinga parameter that changes in absolute value between a time when a flameis not present to a time when a flame is present. Such a change in thedetection signal can still be detected by the control circuit despitethe drifting of absolute values.

While the ignition current is sent to the igniter 120, the valve 110 isheld open by the solenoid 116 for at least an ignition period, which canbe 10 seconds. The flame sensor 140 continues to detect flame from atime before the ignition current is sent until at least a time duringthe ignition period. If presence of a flame is detected (e.g.,rectification of the detection signal received from the flame sensor isidentified) within the ignition period, the solenoid 116 remains activeand the valve 110 remains open. In some implementations, the ignitioncurrent is applied to the igniter 120 for an entire predeterminedignition period, such as 3 seconds, even after the presence of a flamehas been detected. In some implementations, the flame sensorcontinuously monitors the status of flame following detection of thepresence of a flame, the end of an ignition period, or both. The LED 130is updated to a normal status, which can be solid blue. The burner isthen in a normal operation.

In some implementations of the subject technology, if the presence of aflame is not detected (e.g., rectification of the detection signalreceived from the flame sensor is not identified) within the ignitionperiod, the valve 110 is closed. The valve 110 can be closed by thecontrol circuit 150 ceasing to deliver current to the solenoid 116 ofthe valve 110. In some implementations, the control circuit 150 controlsthe LED 130 to indicate a fail status. For example, the control circuit150 can send a signal to the LED or cease delivery of a signal to theLED. A fail status can be indicated by a change to the state of the LED,such as for example, by changing form a continuously illuminated orunilluminated state to a blinking light. The color of the light canadditionally or alternatively be altered, e.g., changed from blue tored.

In a failed ignition state gas has been flowing through a valve for aspecified period of time without detection of the presence of a flame,or with detection of a flame of insufficient stability, at the burner.In some implementations, if the control circuit 150 detects a failedignition state (e.g., by determining that the detection signal from theflame sensor 140 is not rectified, insufficiently rectified, orconsistency of rectification is insufficient) for an entire duration ofthe ignition period or more, the control circuit 150 can close the valve110 and update a status of the LED 130 to indicate ignition failure. Ifthe control circuit 150 detects the presence of flame within theignition period, the control circuit 150 can update a status of the LED130 to indicate normal operational status. In some implementations, thecontrol circuit 150 thereafter monitors, continuously or at intervals, astate of the flame.

In a flame failing state gas has been flowing through a valve and thepresence of a flame was previously detected, or detected to be ofsufficient stability, and during a period in which the valve hasremained open since then a predetermined amount of time has elapsedwithout detection of the presence of a flame, or with detection of aflame of insufficient stability, at the burner. In some implementations,if the control circuit 150 detects a failing state (e.g., by determiningthat the detection signal from the flame sensor 140 is not rectified,insufficiently rectified, or consistency of rectification isinsufficient) for a predetermined period of time during normaloperation, the control circuit 150 can re-energize or otherwisereactivate the igniter 120. The control circuit 150 can update a stateof the LED 130 to indicate performance of an attempt at re-ignition,such as flashing blue as described above. If the control circuit 150does not detect successful ignition (e.g., by determining that thedetection signal from the flame sensor 140 is not rectified,insufficiently rectified, or consistency of rectification isinsufficient) for a predetermined period, the control circuit 150 canclose the valve 110 and update a status of the LED 130 to indicateignition failure. If the control circuit 150 detects the presence offlame within the predetermined period, the control circuit 150 canupdate a status of the LED 130 to indicate normal operational status. Insome implementations, the control circuit 150 thereafter monitors,continuously or at intervals, a state of the flame.

If the control circuit 150 detects a failed ignition state or a failedre-ignition state, the control circuit 150 can close the valve 110 andupdate the LED 130 to indicate a fail status, and the control circuit150 locks out the valve 110 for at least a lockout period, such as 30 or45 seconds, in which the control circuit 150 will not activate thesolenoid 116, to allow the released gas to dissipate.

FIG. 2 shows a flowchart 200 of an example process for operating a grillapparatus 100 according to some aspects of the subject technology. Theexample process of FIG. 2 includes a process for automatically shuttingoff a gas valve of a burner for a grill according to example aspects.FIGS. 3A-3I show tables corresponding to various states during theprocess illustrated by FIG. 2 according to example aspects. At state302, shown in the table of FIG. 3A, the burner starts with (a) a switch(e.g., switch 118) in an off state, (b) the valve (e.g., valve 110)being off such that gas does not flow through the valve, (c) thesolenoid (e.g., solenoid 116) being off, (d) the igniter (e.g., igniter120) off, (e) the burner being off such that no flame is present, and(f) the sensor (e.g., flame sensor 140) is not indicating the presenceof a flame.

In state 304, shown in the table of FIG. 3B, the valve has beenmechanically opened (block 210), which activates the switch (block 212)to an on state. The control circuit 150 begins blinking the LED (e.g.,LED 130) (block 214) to indicate performance of an ignition attempt. Thecontrol circuit 150 activates the igniter (block 216) and applies acurrent to activate the solenoid (block 218) with a 3 second delay. Instate 304, shown in the table of FIG. 3C, the burner is off, and noflame is detected by the control circuit 150 based on a signal receivedfrom the sensor. The control circuit 150 continues to monitor for theflame (block 220) based on a signal received from the sensor.

When the control circuit 150 detects a flame at state 306, the burner ison. The control circuit 150 applies a 3 second delay before shutting offthe igniter (block 222) at state 308, shown in the table of FIG. 3D. Thecontrol circuit 150 continuously powers (turns on) the LED (block 224)to indicate the burner is on.

However, if the control circuit 150 does not detect the presence offlame for at least 3 seconds (block 226) then, at state 310, shown inthe table of FIG. 3E, the control circuit 150 determines that the burneris failing and causes the LED to blink (block 226) to indicate ignitionattempt, and turns on the igniter (block 228) at state 312, shown in thetable of FIG. 3F.

The control circuit 150 monitors for presence of a flame for at least 10seconds (block 230) based on a signal received from the sensor. If thecontrol circuit 150 detects the presence of a flame within the 10seconds, then after applying a 3 second delay the control circuit 150shuts off the igniter (block 232), and continuously powers (turns on)the LED to indicate the burner is on (block 234) to reach a pass state314, shown in the table of FIG. 3G. If the control circuit 150 fails todetect the presence of a flame within the 10 seconds based on the signalreceived from the sensor, the control circuit 150 deactivates thesolenoid to close the passage through the valve (block 236) at the failstate 316, shown in the table of FIG. 3H, although the handle of valvecan still be in an ON position. The control circuit 150 powers the LEDso that it begins blinking (and may change the color to red) to indicatefailure and a need for reset. In certain implementations, if the controlcircuit 150 deactivates the solenoid valve to close the passage throughthe valve, the control circuit 150 keeps the solenoid deactivated for atleast a purge duration, such as 45 seconds, to allow any built up gas topurge. If a handle of the valve is still in the ON position, the handlecan be returned to an OFF position, e.g., physically returned by a user.At the reset state 318, shown in the table of FIG. 3I, the switch isoff, the valve is closed, the solenoid is off, the igniter is off, theburner is off, and the sensor is not indicating the presence of a flame.The reset may place the burner back to the initial setting (e.g., state302).

Although various aspects, features, and exemplifying embodiments of thesubject technology have been described with reference to grills, thesubject technology also can be practiced with other cooking appliances,such as ovens and stoves for example, in the place of the referencedgrills.

As used herein, the phrase “at least one of” preceding a series ofitems, with the terms “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one item; rather, the phrase allows a meaning that includes atleast one of any one of the items, and/or at least one of anycombination of the items, and/or at least one of each of the items. Byway of example, the phrases “at least one of A, B, and C” or “at leastone of A, B, or C” each refer to only A, only B, or only C; anycombination of A, B, and C; and/or at least one of each of A, B, and C.

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically stated, but rather “one or more.” Allstructural and functional equivalents to the elements of the variousconfigurations described throughout this disclosure that are known orlater come to be known to those of ordinary skill in the art areexpressly incorporated herein by reference and intended to beencompassed by the subject technology. Moreover, nothing disclosedherein is intended to be dedicated to the public regardless of whethersuch disclosure is explicitly recited in the above description.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of what can be disclosed, butrather as descriptions of particular implementations of the subjectmatter. Certain features that are described in this specification in thecontext of separate embodiments can also be implemented in combinationin a single embodiment. Conversely, various features that are describedin the context of a single embodiment can also be implemented inmultiple embodiments separately or in any suitable subcombination.Moreover, although features can be described above as acting in certaincombinations and even initially disclosed as such, one or more featuresfrom a disclosed combination can in some cases be excised from thecombination, and the disclosed combination can be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingcan be advantageous. Moreover, the separation of various systemcomponents in the aspects described above should not be understood asrequiring such separation in all aspects, and it should be understoodthat the described program components and systems can generally beintegrated together in a single software product or packaged intomultiple software products.

The subject matter of this specification has been described in terms ofparticular aspects, but other aspects can be implemented and are withinthe scope of the following disclosure. For example, the actions recitedin the disclosure can be performed in a different order and stillachieve desirable results. As one example, the processes depicted in theaccompanying figures do not necessarily require the particular ordershown, or sequential order, to achieve desirable results. In certainimplementations, multitasking and parallel processing can beadvantageous. Other variations are within the scope of the disclosure.

Illustration of Subject Technology as Clauses

Various examples of aspects of the disclosure are described as numberedclauses (1, 2, 3, etc.) for convenience. These are provided as examples,and do not limit the subject technology. Identifications of the figuresand reference numbers are provided below merely as examples and forillustrative purposes, and the clauses are not limited by thoseidentifications.

Clause 1. A system for igniting a grill, the system comprising:

a solenoid valve comprising a switch and a handle, the switch actuatedby manipulation of the handle, the solenoid valve configured to be heldopen by a current;

a flame rectification sensor configured to change a flame detectionsignal,

an igniter; and

a control circuit electrically coupled to the solenoid valve, theswitch, and the flame rectification sensor, the control circuitconfigured to selectively send the current to the solenoid valve whenthe switch is closed, to determine presence of a flame based on thechange to the flame detection signal, and to close the solenoid valvewhen the control circuit does not detect the presence of a flame afteran ignition of the igniter.

Clause 2. The system of clause 1 or any of the clauses, wherein thecontrol circuit is configured to determine presence of a flame bycomparing the flame detection signal before the ignition and the flamedetection signal after the ignition.Clause 3. The system of clause 1 or any of the clauses, wherein thecontrol circuit is configured to determine the presence of a flame bydetermining a derivative of a flame rectifier signal over a period frombefore the ignition to after the ignition.Clause 4. The system of clause 1 or any of the clauses, wherein theflame rectification sensor comprises a spark igniter.Clause 5. The system of clause 1 or any of the clauses, wherein theigniter is configured to ignite a gas using a hot ceramic surface.Clause 6. The system of clause 1 or any of the clauses, furthercomprising a cam member mechanically coupled to the handle, whereinactuating the handle moves a cam of the cam member to close the switch.Clause 7. The system of clause 6 or any of the clauses, wherein the camis configured to hold the switch closed when the handle of the solenoidvalve is in an open position.Clause 8. The system of clause 1 or any of the clauses, wherein thecontrol circuit comprises a power supply circuit.Clause 9. The system of clause 1 or any of the clauses, wherein thecontrol circuit comprises a center-tapped transformer.Clause 10. The system of clause 1 or any of the clauses, wherein thesolenoid valve cannot be opened by the current.Clause 11. A method for igniting a grill, the method comprising:

actuating a handle to mechanically open a solenoid valve, and to move acam configured to close a switch when the handle is moved to open thesolenoid valve, the cam configured to hold the switch closed when thehandle is in an open position;

when the switch is closed, selectively sending a current to the solenoidvalve to hold the solenoid valve open;

in response to the switch closing, sending an ignition current to anigniter to start ignition of the igniter;

determining whether a flame is present based on a change to a flamedetection signal from a flame rectification sensor; and

after the presence of the flame has been determined, monitoring theflame detection signal for continued presence of the flame.

Clause 12. The method of clause 11 or any of the clauses, whereindetermining whether a flame is present comprises reading the flamedetection signal before the ignition and reading the flame detectionsignal after the ignition.Clause 13. The method of clause 11 or any of the clauses, whereindetermining whether a flame is present comprises determining aderivative of a flame detection signal over a period from before theignition to after the ignition.Clause 14. The method of clause 11 or any of the clauses, furthercomprising closing the solenoid valve in response to detecting that noflame is present after a predetermined period after commencing sendingthe ignition current to the igniter.Clause 15. The method of clause 14 or any of the clauses, whereinclosing the solenoid valve comprises ceasing delivery of current to asolenoid of the solenoid valve.Clause 16. The method of clause 14 or any of the clauses, furthercomprising changing an LED to flash a warning color in response todetecting that no flame is present after a predetermined period aftercommencing sending the ignition current to the igniter.Clause 17. The method of clause 11 or any of the clauses, furthercomprising:

determining that flame is no longer present; and

in response to determining that flame is no longer present, sending anignition current to the igniter.

Clause 18. The method of clause 11 or any of the clauses, furthercomprising closing the solenoid valve for at least a lockout period.Clause 19. The method of clause 11 or any of the clauses, furthercomprising commencing flashing of an LED in response to actuation of thehandle to mechanically open the solenoid valve.Clause 20. The method of clause 11 or any of the clauses, furthercomprising continuously powering an LED in response to detection of thepresence of a flame.

In an aspect, any of the clauses herein may depend from any one of theindependent clauses or any one of the dependent clauses. In an aspect,any of the clauses (e.g., dependent or independent clauses) may becombined with any other one or more clauses (e.g., dependent orindependent clauses). In an aspect, a clause may include some or all ofthe words (e.g., steps, operations, means or components) recited in asentence, a phrase or a paragraph. In an aspect, a clause may includesome or all of the words recited in one or more sentences, phrases orparagraphs. In an aspect, some of the words in each of the clauses,sentences, phrases or paragraphs may be removed. In an aspect,additional words or elements may be added to a clause, a sentence, aphrase or a paragraph. In an aspect, the subject technology may beimplemented without utilizing some of the components, elements,functions or operations described herein. In an aspect, the subjecttechnology may be implemented utilizing additional components, elements,functions or operations.

In an aspect, any methods, instructions, code, means, logic, components,blocks, modules and the like (e.g., software or hardware) described orrecited in the clauses herein can be represented in drawings (e.g., flowcharts, block diagrams), such drawings (regardless of whether explicitlyshown or not) are expressly incorporated herein by reference, and suchdrawings (if not yet explicitly shown) can be added to the disclosurewithout constituting new matter. For brevity, some (but not necessarilyall) of the clauses/descriptions are explicitly represented in drawings,but any of the clauses/descriptions can be represented in drawings in amanner similar to those drawings explicitly shown. For example, a flowchart can be drawn for any of the clauses or sentences for a method suchthat each operation or step is connected to the next operation or stepby an arrow. In another example, a block diagram can be drawn for any ofthe clauses or sentences having means—for elements (e.g., means forperforming an action) such that each means—for element can berepresented as a module for element (e.g., a module for performing anaction).

What is claimed is:
 1. A system for igniting a grill, the systemcomprising: a solenoid valve comprising a switch and a handle, theswitch actuated by manipulation of the handle, the solenoid valveconfigured to be held open by a current; a flame rectification sensorconfigured to change a flame detection signal, an igniter; and a controlcircuit electrically coupled to the solenoid valve, the switch, and theflame rectification sensor, the control circuit configured toselectively send the current to the solenoid valve when the switch isclosed, to determine presence of a flame based on the change to theflame detection signal, and to close the solenoid valve when the controlcircuit does not detect the presence of a flame after an ignition of theigniter.
 2. The system of claim 1, wherein the control circuit isconfigured to determine presence of a flame by comparing the flamedetection signal before the ignition and the flame detection signalafter the ignition.
 3. The system of claim 1, wherein the controlcircuit is configured to determine the presence of a flame bydetermining a derivative of a flame rectifier signal over a period frombefore the ignition to after the ignition.
 4. The system of claim 1,wherein the flame rectification sensor comprises a spark igniter.
 5. Thesystem of claim 1, wherein the igniter is configured to ignite a gasusing a hot ceramic surface.
 6. The system of claim 1, furthercomprising a cam member mechanically coupled to the handle, whereinactuating the handle moves a cam of the cam member to close the switch.7. The system of claim 6, wherein the cam is configured to hold theswitch closed when the handle of the solenoid valve is in an openposition.
 8. The system of claim 1, wherein the control circuitcomprises a power supply circuit.
 9. The system of claim 1, wherein thecontrol circuit comprises a center-tapped transformer.
 10. The system ofclaim 1, wherein the solenoid valve cannot be opened by the current. 11.A method for igniting a grill, the method comprising: actuating a handleto mechanically open a solenoid valve, and to move a cam configured toclose a switch when the handle is moved to open the solenoid valve, thecam configured to hold the switch closed when the handle is in an openposition; when the switch is closed, selectively sending a current tothe solenoid valve to hold the solenoid valve open; in response to theswitch closing, sending an ignition current to an igniter to startignition of the igniter; determining whether a flame is present based ona change to a flame detection signal from a flame rectification sensor;and after the presence of the flame has been determined, monitoring theflame detection signal for continued presence of the flame.
 12. Themethod of claim 11, wherein determining whether a flame is presentcomprises reading the flame detection signal before the ignition andreading the flame detection signal after the ignition.
 13. The method ofclaim 11, wherein determining whether a flame is present comprisesdetermining a derivative of a flame detection signal over a period frombefore the ignition to after the ignition.
 14. The method of claim 11,further comprising closing the solenoid valve in response to detectingthat no flame is present after a predetermined period after commencingsending the ignition current to the igniter.
 15. The method of claim 14,wherein closing the solenoid valve comprises ceasing delivery of currentto a solenoid of the solenoid valve.
 16. The method of claim 11, furthercomprising changing an LED to flash a warning color in response todetecting that no flame is present after a predetermined period aftercommencing sending the ignition current to the igniter.
 17. The methodof claim 11, further comprising: determining that flame is no longerpresent; and in response to determining that flame is no longer present,sending an ignition current to the igniter.
 18. The method of claim 11,further comprising closing the solenoid valve for at least a lockoutperiod.
 19. The method of claim 11, further comprising commencingflashing of an LED in response to actuation of the handle tomechanically open the solenoid valve.
 20. The method of claim 11,further comprising continuously powering an LED in response to detectionof the presence of a flame.